1. Field of the Invention
The invention relates to a short arc lamp, especially a lamp in which the body of the main part of the lamp is made of an opaque ceramic and only a front opening is made of a transparent part.
2. Description of the Related Art
Generally, a short arc lamp is formed of quartz glass or the like. However, a special lamp is also used in which the main part of the lamp is made of an opaque ceramic for a special purpose, such as for a medical endoscope.
One such lamp has the advantage that it is extremely durable and easy to handle. For example, such lamps are known from U.S. Pat. Nos. 4,599,540; 4,633,128 and 3,731,133. Specifically, within the ceramic body, a concave space is formed in which gas with increased air pressure is encapsulated, and into the front opening of which a transparent part is installed. In the middle of this concave space are a cathode and anode which form an arc gap. By means of a discharge which is formed in this arc gap, lamp emission is accomplished. In this case, the anode is held on a back end of the body, and the cathode is secured by means of a conductive part which extends from one side of a front end of the body. On the other hand, the transparent part in its vicinity has a U-shaped flange and is attached in the front opening of the above-described body.
Within the lamp, not only this flange, but also a spacer and the like are located. These parts hermetically enclose the inside of the lamp and at the same time have the function of a conductive part for generating the arc.
A lamp of this type does have the advantage of durability and easy handling, as is described above. However, it has the disadvantage that the heat formed in the concave space of the lamp cannot be advantageously dissipated to the outside. In particular, only on the cathode side is there an arrangement in which the main part of the cathode is secured by means of the conductive part. It is difficult to completely transfer the heat by means of this conductive part. Furthermore, the efficiency of heat emission is seriously impaired when the transparent part, the flange, the body and the like are not in complete contact with one another.
If this heat emission is not adequate, a resultant temperature increase of the above-described parts which form the lamp can lead to deformation thereof. In particular, the U-shaped flange, due to its special shape, is easily deformed. If these parts deform and complete contact with the body and the transparent part is destroyed, the hermetically sealed state is destroyed, and furthermore, conductivity is impaired.